Evaluation the potential of indigenous biocontrol agent Trichoderma harzianum and its interactive effect with nanosized ZnO particles against the sunflower damping-off pathogen, Rhizoctonia solani

Abstract

Rhizoctonia solani is a phytopathogenic fungus affecting a wide range of plants hosts including the sunflower causing various diseases such as damping-off. Current management approaches of this pathogen are inadequate. Aim of this study was to assess the potential of eco-friendly control methods, the indigenous biocontrol fungus Trichoderma harzianum and ZnO nanoparticles for controlling of the sunflower damping-off pathogen, R. solani. The biocontrol agent T. harzianum showed a high antagonism effect on R. solani growth. Additionally, growth of R. solani was significantly (p = 0.01) reduced gradually by presence of various concentrations of the ZnO NPs indicating to concentration-dependent toxicity effect. However, a similar impact was also observed on growth of T. harzianum. On the other hand, the percentage of seed germination and stem length of sunflower (Coban cv.) did not affect significantly by ZnO NPs. Conversely, the root lengths were significantly decreased. In the horticultural canopy trial, the best reduction to the sunflower damping-off incidence percentage was achieved by treatment of sunflower seedlings growing in compost inoculated with T. harzianum and R. solani 68.75% comparing to 100% in the control. In contrast, a significant reduction in severity percentage of damping-off symptoms was accomplished in most of the treatments. The best suppression was achieved in treatments of spraying the seedlings with ZnO NPs (15 mg/ml) in two days prior of planting that was 50% in compression with 97.50% in control. These findings can justify the application of the local biocontrol agent T. harzianum alone or in integration with ZnO NPs to be included with current management approaches of sunflower damping-off, which could lead to a diminution in the utilizing of fungicides.